"Cooking is an art". I am interested in not only electronics engineering but also in music, art, and so on. When I cooked, especially in cooking soup or liquid food, it took minutes and minutes to get the soup boiled. I did not like to waste time in waiting in the kitchen so I usually left the kitchen to watch TV or did something else out of the kitchen. Leaving the kitchen might cause the following problems: water boiling over, food being dried out or damaged. How could I solve these problems while cooking, but doing something rather than wasting time in the kitchen? I once had this question in mind, it occurred to me that there must bave been something like a person to tell me about how the cooking was in a progress. A device with a temperature sensor to sense the temperature of the cooked food could tell me about the temperature of the food.
Although there were different kinds of temperature sensors, for economical and simple reasons, I used a silicon transistor as a temperature sensor. I could directly insert the sensor into the food to sense the temperature of the food, but it was troublesome and the sensor might be dirty. I could also sense the temperature of the food indirectly by sensing the temperature of the cooking container. By experiment, I found that when the food was boiling, the temperature of the cover of the cooking container was in a range from 70 to 95 degree in Celsius, depending on the temperature of the environment, the material of the cover, and the strength of the stove.
I have made an electronic cooking alarm device for some time for my use only because there were some problems to install the device and to sense the temperature of the cooking container. I first tried to install the device on a wall near the stove, but it was difficult to install and inconvenient to use the device. Also, the sensor with a pair of flexible wires looked messy, and the wires might be easily melt or burned when the wires were loose to drop near the stove.
Later I tried and tried to finally find out some methods of no installation for the case of the device and of no damage for the sensor and wires. I use magnets attaching the bottom of the case for no installation since almost all stoves have top iron surfaces, and I use two metal tubes as an arm for no damage for the sensor and wires since the arm can support the sensor and protect the wires inside the tubes.
For more purposes of using the device, I add the other sensors and the related circuits to the device to have a practical home security system.
After researching, I find three U.S. Patents similar to my invention. Dennis U.S. Pat. No. 4,315,256 discloses a fire detector having a pair of entwined conductors mounted at the outlet of the chemney; Main U.S. Pat. 3,859,644 discloses a digital cooking timer responsive to the temperature of a cooking medium; and Durkee U.S. Pat. No. 3,686,668 discloses a security system for a building. But these patents are essentially different from my invention of a cooking, fire, and burglar alarm system for homes.